Heavy mobile machines, such as on-and off-highway trucks, are commonly used in mining, construction, transportation, quarrying, logging, and other industries. Many heavy mobile machines employ an internal combustion engine to supply mechanical power to drive a generator. The generator produces electric power, which is used to drive one or more electric motors coupled to the wheels of the machine. An electronic controller regulates the amount of electricity supplied to the motors. For example, as an operator presses an accelerator pedal, the electronic controller will command the generator to supply a corresponding amount of electricity to the traction motors, thereby producing torque to the wheels and moving the machine.
In some machines, the electric motors are induction motors that include a rotor and a stator. Electricity supplied to the stator of the electric motor will produce a rotating magnetic field that induces a current in the rotor. A magnetic field corresponding to the current in the rotor interacts with the rotating magnetic field of the stator, causing the rotor to rotate. Rotation of the rotor is translated into rotation of a machine wheel, thereby moving the machine. While these types of motors are useful in converting electrical energy into mechanical rotation, they may be less than ideal at efficiently using the electricity, especially in mobile machine applications where torque requirements may vary with operating conditions. Therefore, it would be useful to monitor the state of an induction motor in order to determine whether it is operating efficiently, and improve performance, as needed.
One system that monitors an induction motor is described in U.S. Pat. No. 5,726,911, which issued to Canada et al. on Mar. 10, 1998 (“the '911 patent”). In particular, the '911 patent describes a self-contained device that includes various sensors that monitor the state of an induction motor. The sensors include a temperature sensor, a flux sensor, a vibration sensor, and a clock. Based on data collected by these sensors, the health and condition of the motor may be ascertained.
While the system of the '911 patent may be helpful to diagnose some problems associated with a motor, it may not address problems associated with inefficient operation and allocation of electrical energy. For example, while the system of the '911 patent may be capable of determining when a motor is overheating (and therefore should be serviced), it does not address inefficiencies experienced by a motor during operation. In particular, the system of the '911 patent may not address issues that are faced by traction motors in mobile machine applications, such as changes in torque requirements depending on operating conditions.
The present disclosure is directed to overcoming one or more of the problems set forth above and/or other problems of the prior art.